The invention relates to an alignment adjusting device for an optical focal plane assembly. The alignment adjusting device is adapted to be integrated in an optical focal plane assembly comprising a detector having a detector plane and is adapted to be mounted to an optics assembly having an optical focal plane. The alignment adjusting device is adapted for allowing an alignment of the detector plane to the focal plane of the optics assembly, i.e. the optical focal plane.
Alignment adjusting devices are used for light detectors of optical instruments. The light detectors have to be adjusted with regard to the optical path micron precise. An alignment adjusting device which allows such an adjusting enables adjusting the optical focal plane assembly with regard to a predetermined length in any direction and/or around a predetermined angle around any axis. Conventional alignment methods require an exchange of precision stops or wedge rings which have to be manufactured true to dimension. Sometimes, the precision stops and wedge rings have to be dressed or to be newly manufactured. Furthermore, to make a change to the path and/or an angle of rotation it is necessary to exchange precision stops or wedge rings. By exchanging one of these parts, an already set orientation of the members of the alignment adjusting device has to be adjusted again. This makes the alignment process very complicated and time-consuming.
It is an objective of the present invention to provide an alignment adjusting device for an optical focal plane assembly which simplifies the alignment in any direction or around any rotation axis.
This objective is achieved by an alignment adjusting device according to the invention, wherein an alignment adjusting device for an optical focal plane assembly is suggested. The optical focal plane assembly comprises a detector having a detector plane and is adapted to be mounted to an optics assembly having an optical focal plane. The alignment adjusting device is adapted for allowing an alignment of the optical focal plane and the detector plane representing an image area. The alignment adjusting device comprises a detector support for receiving the detector and a plurality of members. A first member of the plurality of members is connected to the detector support and a second member of the plurality of members is connected to a flange that is adapted to be connected to the optics. A first member, the second member and the remaining number of the members are pairwise movable connected to each other by means of a number of springs and/or a number of supporting elements. The number of springs and/or the number of supporting elements is adapted to enable a translational movement along axes of a given coordinate system and/or a rotational movement around the axes of the given coordinate system. The given coordinate system may be a Cartesian coordinate system in which the three axes are arranged at right angles.
The alignment adjusting device makes use of springs and supporting elements, respectively, which allow a movement along one direction (axis) and a rotation around a single axis of rotation. The springs may be lengthened by a specific adjustment. After having finished the adjustment the springs will be fixed. During fixing the adjustment remains unchanged. This allows a separate adjusting of each degree of freedom (each axis of rotation and along each direction). Using of a number of springs and supporting elements allows an accuracy of one micron and five arcseconds, respectively, in any direction. Furthermore, the adjusting may be made in an arbitrary order.
To make the alignment of the optical focal plane and the detector plane, it is not necessary to demount the optical focal plane assembly from the optics assembly. Furthermore, it is not necessary to disassemble the alignment adjusting device in case an adjustment in an arbitrary direction or around an arbitrary axis of rotation is necessary.
Adjusting the optical focal plane and the detector plane may be made by hand or with help of simple standard tools.
According to a preferred embodiment, the number of springs may be adapted to enable the rotational movement around only one of the axes. According to a further embodiment, the number of supporting elements may be adapted to enable the translational movement in only one direction and/or to enable the rotational movement around only one of the axes. This allows an adjustment to be made in an arbitrary order. Furthermore, an adjustment around any of the axes of rotation or along one of the axes can be made independent from each other.
According to a further preferred embodiment, each of the remaining number of members is connected to exactly two other of the members. It is clear, that the first member of the plurality of members which is connected to the detector support is connected to one of the remaining number of members as well. This is a result of the feature that the members are pairwise moveable connected to each other. As well, the second member of the plurality of members which is connected to the flange is connected to one of the remaining number of members.
According to a further embodiment, the plurality of members consists of an intermediate ring representing the second member being connected to the flange by means of detachable lock bolts, an outer frame being firmly connected to the intermediate ring and having a substantially cylindrical shape, an inner frame being coaxially arranged to the outer frame and having a substantially cylindrical shape, a first flexible joint connected to the inner frame, and a second flexible joint representing the first member.
The first axis is the center-line of the coaxially arranged inner and outer frames. The outer frame may be rotated around the first axis with respect to the flange by a predetermined angle. After completion of this adjustment the detachable lock bolts will be fixed to the flange.
According to a further embodiment, each of the adjusting mechanisms may comprise a spring plunger and a first micrometer screw acting on an adjustment bar of the intermediate ring. The adjustment bar may be an integral part of the intermediate ring.
According to a further embodiment, the adjusting mechanism is mounted to the flange and is removable from the flange when the lock bolts are fixed. However, even after disassembling or removing the adjusting mechanism, a rotational movement of the members is no longer possible.
According to a further preferred embodiment, the inner frame is connected to the outer frame by means of three equidistantly distributed adjusted means enabling an adjustment of the inner frame, the first flexible joint and the second flexible joint along the first axis as well as a tilt around a second and a third axis according to the number and a mount of adjustment of the adjusting means.
Each adjusting means may comprise a third flexible joint, a second micrometer screw and a mount, wherein the inner frame is connected with the mount and wherein the third flexible joint is adjustable by the micrometer screw. A translational movement along the first axis may be achieved by a synchronous actuation of the three adjusting means. For a tilt around the second and the third axis the adjusting means, i.e. the micrometer screws, have to be individually rotated.
According to a further preferred embodiment, the alignment along the first axis as well as the tilt around the second and third axis is fixed by corresponding lock bolts. The three micrometer screws may be mounted to the outer frame and wherein the corresponding second micrometer screws may be removable from the outer frame when the lock bolts are fixed. Again, even after removing the three micrometer screws no more change with regard to the movement in the direction of the first axis and around the second and/or the third axis is possible.
According to a further preferred embodiment, the first flexible joint is connected to the inner frame such that, when actuating a corresponding third micrometer screw, a translational movement along the third axis is achieved. In addition, the second flexible joint may be connected to the first flexible joint such that, when actuating a corresponding fourth micrometer screw, a translational movement along the second axis is achieved. The first and the second flexible joint may be actuated independently from each other to achieve the designated adjustment position.
The third and/or the fourth micrometer screws may be removed or demounted by unscrewing after an alignment fixation by means of corresponding bolts.
With regard to the position of the detector support of the alignment adjusting device, the detector support may be attached close to the centre of the second flexible joint. This allows the detector to be positioned symmetrically with regard to the plane defined by the first and third axis as well as by the plane defined by the first and second axis.
The invention will be explained in more detail by reference to the accompanying figures. In the figures, like reference numerals designate like elements.